1. Field of Invention
My invention relates to apparatus for automatic sizing and sorting of celery stalks, plants, and similar articles having somewhat irregular diameters and of a slightly compressible nature.
2. Description of the Prior Art
Celery sizing and sorting is most commonly accomplished manually by the use of a comparatively large number of workers. A worker is trained to examine each stalk of celery coming along a conveyor belt and to judge the size of such stalk. He places each stalk in a container in accordance with its size. Celery is customarily sized by numbers, such as 11/2, 2, 21/2, 3, and 4 with these numbers representing the number of dozen stalks that can be fitted into a standard celery container, such as a crate or carton. While there are celery stalks larger and smaller than these sizes, the present invention is concerned primarily with these five sizes.
With respect to use of workers for sizing and sorting, it has been found that a requirement for rapid operation often results in poor sizing accuracy. Furthermore, the available labor pool for such workers has been decreasing progressively over the past few years. Consequently, a requirement exists for automatic equipment to rapidly and accurately size and sort celery stalks, and similar articles.
Various commercially available devices for sizing articles have been tried for sizing celery stalks. These devices invariably use electronic and electrical switches and devices. However, the presence of washing water, spray, moisture and general wet conditions in celery packing plants have caused such electrical devices to be unreliable and potentially hazardous. An example of an electrical sizer is shown in Buist et al, Pat. No. 3,455,442. In that invention, the stalks are carried along by two spaced conveyor Vee-belts riding on pulleys. The stalks pass under a series of height detectors, each set for a different size. The detector arm, when moved to its set height, closes an electrical switch which energizes a solenoid. The solenoid kicks the stalk so that it falls between the two Veebelts, into means for distributing the stalks to the proper crates. This approach has several disadvantages which are overcome in the present invention. The rigid height-measuring arms may cause inaccurate sizing due to unsymmetrical stalks. No method of holding the stalks in position on the conveyor Veebelts are shown, and electrical contacts are used.
Several other sizing or sorting devices are known but none of these are completely satisfactory for celery sizing. Eggers U.S. Pat. No. 3,250,388 and Preu et al U.S. Pat. No. 3,241,666 teach apparatus for sensing the size of solid objects on a line or conveyor. The forces required in the sensing precludes the use of these devices for celery or other easily damaged, compressible material.
An apparatus by Goodall, U.S. Pat. No. 3,645,394 for sorting and grading cut flowers, uses electrical contacts and solenoids for sorting according to stem lengths. U.S. Pat. No. 3,468,415 to Sarver is basically a simple sensor type device for sorting irregularly shaped items, and involves several rigid arms, electrical contacts, and a solenoid for kicking irregularly shaped objects off of a conveyor belt when they exceed a certain size.
Another approach attempted in the past has been to size and sort by weight. However, this method has proven to be inaccurate with the type of equipment capable of operating in the wet conditions present in celery packing plants.
My invention overcomes the various problems and limitations of these known prior art devices. As will be described in more detail hereinafter, I utilize air-operated relays, controls and actuators thereby providing high reliability, as well as safety in a wet environment. Stalks of celery are held in place in holders configured as metal baskets, obviating accidental dislodgement of stalks. Size is measured at one station by a soft flexible band that contacts the stalks at several points around the periphery thereby obtaining a good average of unsymmetrical stalks. Whereas most of the devices previously known utilize rigid arms, cams, levers, etc. in the sizing operation with an inherent danger of bruising or damaging celery stalks, the use in accordance with this invention of a soft, flexible nonelastic band for sizing prevents such damage.